Reverb and delay are echo-based effects that home recordists routinely use on all manner of instruments and vocals in order to give them a little depth and sense of space. Delay emulates the effect of a sound wave reflecting off a surface and reaching the ear more than 0.1 second after the initial signal. This results in an audible echo of the original sound. When the delay time is less than 0.1 seconds, the reflected wave isn't audible as separate from the original. Rather, the two combine to make the prolonged, spacey sound known as reverberation. Delay and reverb effects can add excitement to a multi-track recording if used sparingly. Overuse of these effects tends to reduce clarity and presence, moving sounds further into the background of a mix.
The chorus effect is similar to reverb and delay in that home recordists mix two slightly out-of-sync signals together. The difference is that they detune the returned signal slightly from the original, which creates a wide, shimmering effect. Home recordists can operate rate and depth controls on chorus processors to fine-tune this pitch shifting and achieve the desired sound. Low rate and depth settings are subtle and add a little fullness to the sound; high settings yield results that are more dramatic, adding a warbling effect. Chorus effects can be very effective in adding dimension to guitars and a little character to vocals, but like delay and reverb, are best used sparingly. Overdoing the chorus, especially at high rates can make a track sound like a detuned mess.
The basic role of a compressor is to control the dynamic range of an instrument or vocal track. Often, a track will have loud sections and quieter ones, and it can be difficult to get a good strong signal during the quieter passages without the peaks overloading and distorting the track. A compressor limits the peaks and raises the quieter parts of the signal, effectively squashing the dynamic range. This gives tracks more consistency and punch to vocals, and can even add sustain when used on guitar tracks.
Home recordists use equalization, or EQ, to fine-tune the tonal characteristics of instruments and voices so that they blend to create a cohesive-sounding mix. Graphic equalizers have faders that home recordists operate for the cutting or boosting of set frequencies on a recorded track. If two instruments in a recording are strong in a similar frequency, they may compete with each other for sonic space in the mix. Often, a slight cut in the frequency on one of the tracks is enough to give the two instruments the required separation for a cleaner mix. Cutting EQ is often preferable to boosting it, since any boost adds noise, which can cause distortion and make a mix sound muddy.
If a recorded vocal sounds a little thin, doubling it is one way to beef it up and give it more punch. Home recordists can operate multi-track recorders to copy a recorded part to another track and have the two tracks play simultaneously, although this method can tend to sound a little sterile. A more common approach is the re-recording of the vocal on a second track and the playback of the two performances together. This ability to emulate the first vocal's inflections and phrasing is a skill that takes practice for most musicians. Yet, when done right, the resulting vocal take sounds fuller, smoother and has a more professional sheen.